[plt-scheme] glitch in documentation for PLAI?

I'm using 4.2.1. I loaded the Planet file for PLAI as described on the 
PLAI web page, and restarted DrScheme. Working in the PLAI Scheme 
language works fine. I can load the PLAI documentation page, visible 
from the index page of Help Desk. But when I try to use the "top" link 
by the search box, my browser says "file not found":

file:///Users/plragde/Library/PLT%20Scheme/planet/300/4.2.1/cache/plai/plai.plt/1/3/doc/index.html

I get a similar error when I try to search using the search box (the 
missing file is .../1/3/doc/search/index.html). --PR